Best treatment for speaker feet????


Looking for input on best way to handle speaker feet. Couple or decouple? Spikes or rubbber? Granite or no granite?

My situation is, 80lb floorstanding speakers on carpet over plywood decking on second floor.

Opinions appreciated!
jaxwired
The underlying principle here is that the speaker (enclosure/frame) must be "mass coupled" to the floor (or, preferrably, to the planet!) so that the only thing that can move is/are the drivers. Spikes are simply the easiest and least destructive solution in most cases. But you could, for instance, bolt your speakers right to the floor;--)

And then of course, there's the issue of floor itself: it mustn't move at all. This is often a problem with wood framed (joisted) floors where the subfloor can deform (bend) slightly as it spans between joists. However, there are some tricks (which are obvious to architects and builders) that will minimize the effect of this common type of floor deformation:
1.) The best situation is if the speakers point (front to back) along the same direction as the floor joists. This is most likely to happen automatically if the speakers are placed on the long wall, since joists are usually oriented to span the short dimension of the room. Why is this (long wall) placement best? Because the subfloor's movement (if any) only allows the speaker to rock from side-to-side in this case. But the drivers only move forward/backward, but the direction of the floor joists in this case, prevents the speakers from reacting (rocking) front-to-back; it they did/could, it would rob the drivers of energy they could/should be transferring to the air! This condition would also reduce the drivers' transient response (accuracy in following the signal) -- a problem that particularly degrades the midrange. Of course, they can STILL (possibly) rock from side to side, but that WON'T MATTER unless your speakers have side-firing woofers ;--) Of course there are other acoustic benefits to 'long-wall' placement.
2.) So if you are lucky, and able to orient your speakers in line with the direction of the floor joists as described above, you'll do even better to 'center' the speaker (left-to-right) over the space BETWEEN two joists, as opposed to it straddling a single joist. This will mostly eliminate side-to-side rocking -- although this is less critcal as I explained above.

Implementing these "tricks", if you can, will result in a huge improvement in transient response; e.g. detail and clarity of vocals, plus cleaner (more slam) in the bass response. And it's free ;--)

3.) Unfortunately for many of us, there are multiple reasons we're unable to place our speakers along the long wall, as in 1.) and 2.), however, it's still possible to realize many of the same benefits (minimizing forward/backward rocking) if you will crawl under the floor and actually locate the two joists (now running side to side across the room) which are nearest the speaker -- the one closest in front of the desired speaker location, and the one running closest behind, and mark their location on the floor above. Then center the speaker(s) front to back BETWEEN those two joists -- again, as opposed to the speaker straddling across just one joist. This "trick" will further minimize forward/backward rocking -- the taller/heavier the speaker, the greater the benefit; although, even with monitors on stands, it still really helps to increase the speakers' effective mass by filling those stands with sand or shot. BTW, it's OK to add toe-in to the speakers, but wait until after you've determined the best location relative to the floor joists.
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I would stay away from granite. IMO, you need to ABSORB, not REFLECT. What I believe happens with granite for example, is the drivers move causing vibrations in the cabinet. Those vibrations travel down the cabinet, through the spikes, into the granite. Then, those vibrations bounce off of the granite, travel up through the spikes and back into the cabinet. I believe you should spike the speakers into a maple block to absorb vibrations. You can buy small spikes/cones and place them under the maple into the floor. Just my theory....
I use a inch and a half thick slab of black granite under my floorstanding speakers. The speakers have cones and feet protectors which I purchased from Adona, sitting on top of the granite. As the speakers weigh 85 pounds each, they are extremely stable. In my case, It made a tremendous difference over just having the sharp cones going through the carpet to the wood floor below. Bass impact is much better now with no smearing and everything seems more defined. I am currently using Odyssey Kismet Reference speakers and also used this combination on a pair of DeVore Gibbon 8 speakers a few years ago. The results were pretty much the same.

I will say that the cost of the granite was a bit pricey, I believe I paid around 100.00 for a pair of 10" by 14" pieces 1 1/2 inches thick, polished on all edges as well as the top.
Devilboy, spikes when placed under speakers, are for mass-coupling the speakers to the floor. Nothing more, nothing less. As I said, you could bolt the speakers to the floor and acheive the same thing, maybe better! The speaker designer engineered his speaker as if it would be operated in a COMPLETELY RESTRAINED state -- the specified performance of the drivers he used depend on it! If you say things sound better than with the spikes going through the carpet and into the floor, I would offer that the granite slab is now probably bridging across the joists underneath, whereas before, without the granite, and unbeknownst to you, the spikes just happened to be landing on one of those weak places in the floor, as I described in my post. I can't tell you how many times I've seen audiophiles fooled by not recognizing this oversight! (Same comment applies to Stereo5's experience.) You guys should go back and review exactly WHERE on your wood floors the spikes were originally landing, relative to the joists underneath -- and then reposition the speakers as I recommended! Then you can tell me about how great the granite works;--)

As for the comments about
vibrations travel down the cabinet, through the spikes, into the granite. Then, those vibrations bounce off of the granite, travel up through the spikes and back into the cabinet.
that is just patently impossible! The whole point of spikes and cones (especially when used under electronic components and turntables, etc.) is to act as MECHANICAL DIODES; meaning vibrations travel out the pointed tip, but CANNOT return back the other way! If the speaker cabinet is vibrating, either the designer meant it to, as in many of the English bookshelf speakers, or, more likely, the enclosure is inadequately braced! The only "vibrations" a speaker should produce are the ones from the drivers when coupling them to the air!

Further, you are certainly doing your speakers no justice by placing them on a "carpet sandwich"! I don't care if the granite slab weighs 500 lbs! It will still allow the speaker to rock. Even a few micrometer 'squish' at the speaker's base, will translate into a few millimeters of sway at the top of the enclosure (you know, where the tweeters are located?) and that is enough to cause doppler distortion in the high frequencies coming from those tweeters.

Go back and examine your floors and determine the location and direction of the joists. Then position your speakers as I indicated and I guarantee, you'll get better performance than you have so far -- that's for sure! All that speculative pseudo-science is the devil! -- only physics will set you free ;--)
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Spikes I suppose.

My large OHM 5 floorstanders use locking castors, which works very well given the pyramidal form but is not practical for many tall rectangular floorstanders probably. Castors also facilitate easy movement and tweaking of placement as needed.